/*
 * Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package javax.imageio.plugins.jpeg;

import java.util.Arrays;

/**
 * A class encapsulating a single JPEG Huffman table.
 * Fields are provided for the "standard" tables taken
 * from Annex K of the JPEG specification.
 * These are the tables used as defaults.
 * <p>
 * For more information about the operation of the standard JPEG plug-in,
 * see the <A HREF="../../metadata/doc-files/jpeg_metadata.html">JPEG
 * metadata format specification and usage notes</A>
 */

public class JPEGHuffmanTable {

  /* The data for the publically defined tables, as specified in ITU T.81
   * JPEG specification section K3.3 and used in the IJG library.
   */
  private static final short[] StdDCLuminanceLengths = {
      0x00, 0x01, 0x05, 0x01, 0x01, 0x01, 0x01, 0x01,
      0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  };

  private static final short[] StdDCLuminanceValues = {
      0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
      0x08, 0x09, 0x0a, 0x0b,
  };

  private static final short[] StdDCChrominanceLengths = {
      0x00, 0x03, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
      0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
  };

  private static final short[] StdDCChrominanceValues = {
      0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
      0x08, 0x09, 0x0a, 0x0b,
  };

  private static final short[] StdACLuminanceLengths = {
      0x00, 0x02, 0x01, 0x03, 0x03, 0x02, 0x04, 0x03,
      0x05, 0x05, 0x04, 0x04, 0x00, 0x00, 0x01, 0x7d,
  };

  private static final short[] StdACLuminanceValues = {
      0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
      0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
      0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,
      0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,
      0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,
      0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,
      0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
      0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
      0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
      0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
      0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
      0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
      0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
      0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
      0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
      0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5,
      0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4,
      0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2,
      0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
      0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
      0xf9, 0xfa,
  };

  private static final short[] StdACChrominanceLengths = {
      0x00, 0x02, 0x01, 0x02, 0x04, 0x04, 0x03, 0x04,
      0x07, 0x05, 0x04, 0x04, 0x00, 0x01, 0x02, 0x77,
  };

  private static final short[] StdACChrominanceValues = {
      0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,
      0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,
      0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,
      0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,
      0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34,
      0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26,
      0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38,
      0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
      0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
      0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
      0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
      0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
      0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,
      0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,
      0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4,
      0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3,
      0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2,
      0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda,
      0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,
      0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
      0xf9, 0xfa,
  };

  /**
   * The standard DC luminance Huffman table.
   */
  public static final JPEGHuffmanTable
      StdDCLuminance = new JPEGHuffmanTable(StdDCLuminanceLengths,
      StdDCLuminanceValues, false);

  /**
   * The standard DC chrominance Huffman table.
   */
  public static final JPEGHuffmanTable
      StdDCChrominance = new JPEGHuffmanTable(StdDCChrominanceLengths,
      StdDCChrominanceValues, false);

  /**
   * The standard AC luminance Huffman table.
   */
  public static final JPEGHuffmanTable
      StdACLuminance = new JPEGHuffmanTable(StdACLuminanceLengths,
      StdACLuminanceValues, false);

  /**
   * The standard AC chrominance Huffman table.
   */
  public static final JPEGHuffmanTable
      StdACChrominance = new JPEGHuffmanTable(StdACChrominanceLengths,
      StdACChrominanceValues, false);

  private short[] lengths;
  private short[] values;

  /**
   * Creates a Huffman table and initializes it. The input arrays are copied.
   * The arrays must describe a possible Huffman table.
   * For example, 3 codes cannot be expressed with a single bit.
   *
   * @param lengths an array of {@code short}s where <code>lengths[k]</code> is equal to the number
   * of values with corresponding codes of length <code>k + 1</code> bits.
   * @param values an array of shorts containing the values in order of increasing code length.
   * @throws IllegalArgumentException if <code>lengths</code> or <code>values</code> are null, the
   * length of <code>lengths</code> is greater than 16, the length of <code>values</code> is greater
   * than 256, if any value in <code>lengths</code> or <code>values</code> is less than zero, or if
   * the arrays do not describe a valid Huffman table.
   */
  public JPEGHuffmanTable(short[] lengths, short[] values) {
    if (lengths == null || values == null ||
        lengths.length == 0 || values.length == 0 ||
        lengths.length > 16 || values.length > 256) {
      throw new IllegalArgumentException("Illegal lengths or values");
    }
    for (int i = 0; i < lengths.length; i++) {
      if (lengths[i] < 0) {
        throw new IllegalArgumentException("lengths[" + i + "] < 0");
      }
    }
    for (int i = 0; i < values.length; i++) {
      if (values[i] < 0) {
        throw new IllegalArgumentException("values[" + i + "] < 0");
      }
    }
    this.lengths = Arrays.copyOf(lengths, lengths.length);
    this.values = Arrays.copyOf(values, values.length);
    validate();
  }

  private void validate() {
    int sumOfLengths = 0;
    for (int i = 0; i < lengths.length; i++) {
      sumOfLengths += lengths[i];
    }
    if (sumOfLengths != values.length) {
      throw new IllegalArgumentException("lengths do not correspond " +
          "to length of value table");
    }
  }

  /* Internal version which avoids the overhead of copying and checking */
  private JPEGHuffmanTable(short[] lengths, short[] values, boolean copy) {
    if (copy) {
      this.lengths = Arrays.copyOf(lengths, lengths.length);
      this.values = Arrays.copyOf(values, values.length);
    } else {
      this.lengths = lengths;
      this.values = values;
    }
  }

  /**
   * Returns an array of <code>short</code>s containing the number of values
   * for each length in the Huffman table. The returned array is a copy.
   *
   * @return a <code>short</code> array where <code>array[k-1]</code> is equal to the number of
   * values in the table of length <code>k</code>.
   * @see #getValues
   */
  public short[] getLengths() {
    return Arrays.copyOf(lengths, lengths.length);
  }

  /**
   * Returns an array of <code>short</code>s containing the values arranged
   * by increasing length of their corresponding codes.
   * The interpretation of the array is dependent on the values returned
   * from <code>getLengths</code>. The returned array is a copy.
   *
   * @return a <code>short</code> array of values.
   * @see #getLengths
   */
  public short[] getValues() {
    return Arrays.copyOf(values, values.length);
  }

  /**
   * Returns a {@code String} representing this Huffman table.
   *
   * @return a {@code String} representing this Huffman table.
   */
  public String toString() {
    String ls = System.getProperty("line.separator", "\n");
    StringBuilder sb = new StringBuilder("JPEGHuffmanTable");
    sb.append(ls).append("lengths:");
    for (int i = 0; i < lengths.length; i++) {
      sb.append(" ").append(lengths[i]);
    }
    sb.append(ls).append("values:");
    for (int i = 0; i < values.length; i++) {
      sb.append(" ").append(values[i]);
    }
    return sb.toString();
  }
}
